EP0160909A2 - Process for the chlorination and sulphochlorination of organic compounds - Google Patents

Abstract

Process for the chlorination and sulfochlorination of fat raw materials, in which the reactants are circulated through a reaction zone into which the chlorine and SO2 are fed in cocurrent with the liquid fat raw material and homogenized by an intensive mixer.

Description

The invention relates to an improved method for reacting chlorine and mixtures of chlorine and sulfur dioxide with liquid or dissolved organic components. The method is particularly advantageous when the liquid phase to be treated has or assumes an increased viscosity under reaction conditions. The process is particularly suitable for the chlorination and sulfochlorination of fatty raw materials, in particular fatty acids and / or their esters with mono- and / or polyhydric alcohols. In the context of the teaching according to the invention, the term chlorination encompasses both the addition of chlorine to olefinic double bonds of the starting material and the substitution reaction which may be excited by UV light to form HC1. The term “sulfochlorination” encompasses in the usual way the reaction of SO ₂ / Cl ₂ mixtures with aliphatic chain constituents, possibly excited by UV light, with formation of the SO ₂ Cl group and emission of HC1.

The chlorination and sulfochlorination of fat raw materials, in particular fatty acids and / or fatty acid esters, is known to lead to interesting fatliquoring agents for leather and furs. Thus, from DE-PS 22 45 o77 such fatliquors based on sulfonated chlorination products of natural or synthetic higher fatty acids or fatty acid esters in the form of their alkali, ammonium or amine salts are known, which are characterized in that they consist of such sulfonated chlorination products, those by chlorinating higher fatty acids or higher esters Fatty acids of chain lengths C ₈ - C ₂₄ up to a chlorine content of 2o to 45 percent by weight have been obtained, the chlorination products essentially no longer containing olefinic double bonds and the subsequent sulfonation with S0 ₃ up to a content of 40 to 100 mole percent S0 ₃ , based on the chlorination product.

Corresponding fatliquoring is further described in DE-OS 3o 18 176, this teaching being characterized in that the fatliquoring consists essentially of those sulfonated chlorination products which are chlorinated by sulfochlorinating higher fatty acids or esters of higher fatty acids of chain lengths C ₈ - C ₂₄ and S0 _2, if appropriate with UV irradiation at 2o to 9o ° C up to a content of bound chlorine of 5-30% by weight and a content of S0 ₂ C1 groups of 1 to 20% by weight, the ratio of chlorine atoms to SO ₂ Cl groups is in the range from o, 7: 1 to 7o: 1. and a subsequent saponification of these groups has been carried out. An improvement is described in DE-OS 32 38 741.5, with higher fatty acid or fatty acid ester mixtures which contain unsaturated portions now being used in the preparation of the sulfonated chlorination products. In this case, chlorination is first carried out to saturate the double bonds and then sulfochlorination with chlorine and SO ₂ . The subsequent saponification leads to the desired fatliquoring agents.

Under the reaction conditions of chlorination / sulfochlorination, chlorine and SO _{2 are in} gaseous form. In order to be able to react with the organic reactant, these gaseous components must be dissolved in the liquid phase. For this purpose, the gases are usually passed from below into a liquid column via gas distributors, or gaseous and liquid reactants are run in countercurrent to one another through exchange devices, for example packed columns. It turns out, however, that the viscosity of the organic liquid phase increases with increasing reaction. At the same time, the exchange of materials between liquid phase and gas phase increasingly inhibited. For example, in a column of the liquid reactant into which the gaseous reactants are fed at the bottom, as the viscosity of the liquid phase increases, larger and larger bubbles rise rapidly. The gaseous components fed to the reactor increasingly leave the reactor in the unreacted state. The rate of conversion, which is influenced by the mass transfer rate of the gases into the liquid phase, decreases. With simultaneous absorption and reaction of several gases, the different solubility of the gases in the liquid phase influences the course of the reaction.

The teaching of the invention is based on the surprising finding that, despite the miscibility of gas and liquid phases that is increasingly difficult in the course of the reaction to be observed, homogenization of the reaction mixture can be achieved in particular in the stages of the course of the reaction by additional action of mechanical forces optical appearance of the reactant mixture speaks against good miscibility.

The invention accordingly relates to a process for chlorination and sulfochlorination of fat raw materials which are liquid under reaction conditions, in particular fatty acids and / or their esters, by reaction with chlorine and SO ₂ , in which the liquid feed is circulated through a reaction zone in which it is reacted with chlorine and S0 ₂ fed into the circuit, the new process being characterized in that the chlorine and S0 _{2 are} fed in cocurrent with the liquid material and together with it during or before entering the reaction zone by a Intensive mixer are performed, the amount of chlorine and S0 ₂ fed so that the reaction mixture passes through the reaction zone as a practically homogeneous liquid phase.

The principle of the method according to the invention can be seen from the flow diagram of the attached FIG. 1: Sulfochlorinating liquid is fed from the container B to the mixing device R by the pump P. Shortly before entry - or upon entry - into R, the gaseous reactant or the corresponding reactant mixture is expediently introduced into the circulating liquid through a coaxial tube. Static and / or moving mixing elements inserted into the liquid circuit can be used as the mixing zone, preference being given to working with static mixing elements which, by means of intersecting guide elements in the region of the mixing zone, bring about a highly turbulent zigzag flow of the gas-liquid mixture.

Due to the intensive mechanical mixing of the gas-liquid phase in the mixing device R, the gas phase is completely or practically completely dissolved in the increasingly viscous liquid phase despite the short residence time of the reaction mixture in this mixing device. In the preferred embodiment of the invention, the liquid which leaves the mixing zone R contains virtually no visible gas bubbles. It is returned to the container B via the reaction zone C and then through a heat exchanger W. Here, the HCl that may be formed degasses and can be fed to a scrubber.

• Die Umsetzungsgeschwindigkeit kann nicht durch den Stoffübergang gas-flüssig limitiert werden, die unterschiedlichen Löslichkeiten von Chlor und S0₂ in der Flüssigphase haben damit keinen Einfluß auf den Reaktionsablauf. Chlor und S0₂ haben eine einheitliche Verweilzeit in der Reaktionszone, d. h. ein enges Verweilzeitspektrum. Die Verweilzeit von Chlor bzw. S0₂ in der Reaktionszone wird nur durch den Flüssigkeitskreislauf bestimmt. Ein Durchschlagen von nicht reagiertem Gas ist nicht möglich. Es-können Flüssigphasen mit hoher Viskosität eingesetzt werden, die bisher wegen des Durchschlagens der Gasphase wirtschaftlich der Umsetzung nicht zugeführt werden konnten. Die Reaktion selbst kann bei niedrigeren Temperaturen - und damit entsprechend höheren Viskositäten der Flüssigphase - durchgeführt werden, was beispielsweise hinsichtlich der Selektivität der Sulfochlorierung von Vorteil ist. Die Viskosität beeinfluß damit nicht mehr die Wahl der Reaktionstemperatur. Die Sulfochlorierung kann damit problemlos bei einem Einsatzmolverhältnis von Chlor zu SO₂ von 1 : 1 durchgeführt werden, ohne daß gleichzeitig Kettenchlorierung eintritt oder es zu wesentlichen S0₂-Verlusten kommt. Dies ist beispielsweise von Interesse, wenn preisgünstige Fettstoffe mit höherer Jodzahl zum Einsatz kommen. Mit diesen Fettstoffen kann zunächst eine Chloraddition an die olefinische Doppelbindung und anschließend eine Sulfochlorierung ohne Kettenchlorierung durchgeführt werden. Für denselben Kettenchlorgehalt wird bekanntlich bei der Additonsreaktion nur halbsoviel Chlor verbraucht wie bei der Substitutionsreaktion.

The procedure described allows the reaction to take place in a single-phase, homogeneous medium. This has the following advantages, among others:

• The rate of conversion cannot be limited by the gas-liquid mass transfer, the different solubilities of chlorine and SO ₂ in the liquid phase therefore have no influence on the course of the reaction. Chlorine and SO ₂ have a uniform residence time in the reaction zone, ie a narrow residence time spectrum. The residence time of chlorine or SO ₂ in the reaction zone is only determined by the liquid cycle. It is not possible to blow through unreacted gas. Liquid phases with a high viscosity can be used, which have so far been economical because of the breakdown of the gas phase could not be fed. The reaction itself can be carried out at lower temperatures - and thus correspondingly higher viscosities of the liquid phase - which is advantageous, for example, with regard to the selectivity of the sulfochlorination. The viscosity no longer influences the choice of reaction temperature. The sulfochlorination can thus be carried out without problems at a molar ratio of chlorine to SO ₂ of 1: 1, without chain chlorination occurring at the same time or significant S0 ₂ losses occurring. This is of interest, for example, if inexpensive fatty substances with a higher iodine number are used. These fatty substances can first be used to add chlorine to the olefinic double bond and then to carry out sulfochlorination without chain chlorination. For the same chain chlorine content, it is known that only half as much chlorine is used in the additon reaction as in the substitution reaction.

The new process is particularly suitable for the chlorination / sulfochlorination of fatty substances such as triglycerides, fatty acids and / or their esters. Examples are tallow, tallow fatty acid methyl ester, coconut fatty acid methyl ester follow-up, LT follow-on esters and mixtures thereof.

The invention preferably starts from higher fatty acids or from esters of such higher fatty acids of chain lengths C ₈ -C ₂₄ , in particular C _lo -C ₂₀ , with iodine numbers of lo-12o. Mixtures of fatty acids from naturally occurring fats or oils with a proportion of mono- or polyunsaturated fatty acids are preferred. Examples of these are the fatty acid mixtures or their esters obtained from coconut oil, soybean oil, palm kernel oil, cottonseed oil, rapeseed oil, linseed oil, castor oil, sunflower oil, olive oil, claw oil, peanut oil, herring oil, cod oil, shark oil, walnut oil, tallow fat or lard. Also the corresponding naturally occurring fats or oils and naturally occurring wax esters, e.g. B. sperm oil, are suitable as starting material for the production of fatliquors of the type described. It is crucial that the Carrying out the chlorination and sulfochlorination is no longer hindered by the high viscosity of the corresponding liquid phases or reaction products resulting therefrom.

Particularly preferred as starting materials for the preparation of the fatliquoring agents are synthetically produced esters from mixtures of saturated and unsaturated fatty acids of chain lengths C ₈ to C ₂₄ , preferably C ₁₀ to C2o, with iodine numbers of lo to 12o, for example decanecarboxylic acid, palmitic acid, stearic acid, behenic acid, dodecenecarboxylic acid , oleic acid, linoleic acid or carboxylic acids produced by paraffin oxidation and their esters with monohydric aliphatic alcohols of chain lengths C ₁ to C ₄ . Because of their easy accessibility, the transesterification products prepared from natural animal or vegetable fats, oils or waxes with the lower monohydric aliphatic alcohols, in particular methanol, may also be preferred. Other alcohols suitable for ester formation are: polyhydric aliphatic alcohols with chain lengths C ₂ to C ₆ such as ethylene glycol, 1,2-propylene glycol, glycerol, pentaerythritol or sorbitol or higher alcohols with chain lengths C ₈ to C ₂₄₁ such as decyl alcohol or oleyl alcohol,

In a preferred embodiment of the invention, the reaction is carried out in the absence of viscosity-reducing diluents. As is known, to solve the viscosity problem in the field concerned here, it was also proposed to achieve an improved mass transfer between the gas and liquid phases by the use of inert viscosity-reducing diluents.

For example, commercially available rotor-stator machines are suitable as mixing elements - see Figure 1 R. In these devices, the high-speed rotors create a mechanical shear effect between the rotor and the stator. Due to this shear effect, the gas is in the mix during the short residence time device completely solved. The homogeneous or practically homogeneous liquid phase which leaves the rotor-stator machine is fed to the reaction zone G which is usually irradiated with a UV lamp.

In a preferred embodiment of the invention, static mixing elements are used. These are also commercially available aids. Installation bodies made of corrugated and often bent, intersecting are suitable, for example. Expanded metal strips. In such a system of intersecting channels, a highly turbulent zigzag flow of the mixture of liquid phase and gaseous reactants is guaranteed. This achieves intensive mixing and ultimately homogenization of the reaction phase. For the relevant literature, reference is made, for example, to W. Tauscher, The Wide Range of Applications of the Static Mixer, Chemical Production (1977) lo, lo-14. Suitable static mixing elements from Gebrüder Sulzer AG, Winterthur, Switzerland, for example, are suitable, which are sold, for example, under the trade name "SMV".

The following preferred method specifications apply in particular when working with such static mixing elements built into the flow tube: Flow rates of the liquid phase in the static mixing zone - based on the empty tube - in the range of 0.1 to 5 m / s, preferably in the range of 0.1 25 to 2.5 m / s. Preferred ratio of length to diameter of the mixing section in the range from 2: 1 to 20: 1. With comparatively short mixing sections, which can be approximately in the range from 10 to 50 cm, intensive mixing in the sense of the invention is achieved. The ratio of the amount of gas supplied to the circulating amount of liquid for the two reaction gases chlorine and SO ₂ is in each case generally in the range from 0.50 to 500 parts by weight gas / 100 parts by weight liquid, in particular in the range from 0.1 to 100 parts by weight gas and preferably in the range from 0 , 3 to 3o parts by weight of gas - in each case based on looo parts by weight of liquid.

Chlorine and sulfur dioxide can be metered in as gaseous reactants but also under pressure as liquids in the circulating stream of the liquid reactant, depending on the pressure and temperature at the point of introduction, they either evaporate or are dispersed and dissolved as a liquid. The pressure at the point of introduction of chlorine and / or sulfur dioxide is preferably in the range from 0.2 to 80 bar, in particular in the range from 0.2 to 25 bar and advantageously in the range from 0.5 to 5 bar.

If several steps are carried out according to the invention in such a way that the addition of chlorine to existing olefinic double bonds takes place in a first reaction stage and the sulfochlorination stage subsequently takes place, it may be preferred to add the chlorine in the temperature range from about 50 to 70 ° C. and the sulfochlorination Carry out temperatures of about 3o to 5o ° C.

The duration of the reaction is generally about 2 to 10 hours. After this time, for example, 5 to 30 percent by weight of chlorine and 1 to 20 percent by weight of SO ₂ Cl groups have been added. The ratio of chlorine atoms to SO ₂ C1 groups is preferably in the range from about 0.7: 1 to 70: 1, in particular the ratio is 2: 1 to 20: 1, advantageously 3: 1 to 7: 1.

Subsequent saponification, for example with aqueous approximately 30% sodium potassium hydroxide solution at approximately 70 ° C., gives liquid, highly concentrated water-emulsifiable products with excellent oxidation, light and acid stability, which are outstandingly suitable, for example, for leather greasing, as described in DE OS 32 38 741.5 is described in detail.

The following examples describe both the addition of chlorine to the olefinic double bonds present and the sulfochlorination in a molar ratio of 1: 1 and, if appropriate, a subsequent substitution by chlorine at higher viscosities.

example 1

841 kg of tallow fatty acid methyl ester at 20 ° C (JZ = 52) are filled into the container B shown in Figure 1 and pumped around by means of the pump p with a throughput of 15 m ³ / h. Without igniting the UV lamp in reaction zone G, 54 kg of chlorine / h are introduced, the product temperature rising to 61 ° C. After the chlorine content of the product has reached 14 percent by weight, the mixture is cooled to 40 ° C. and the UV lamp is switched on in reaction zone G. There are now 2o kg / h of chlorine and 18 kg / h introduced S0 ₂ until the SO ₂ Cl content of the reaction product is 15 percent by weight. The chain chlorine content has not changed. Now the S0 ₂ inflow is switched off and chlorination is carried out under the same operating conditions with 2o kg C1 _{2 /} h up to a chain chlorine content of 18%. 125o kg of tallow fatty acid methyl ester sulfochloride are obtained.

.. During the reaction the viscosity of the liquid phase increases to 3oo mPas at 4o ° C. In spite of this, the rotor-stator mixer provided in the mixing zone R does not reveal any gas bubbles in the circulating liquid phase behind the mixing device when it is running. However, if the rotor-stator machine is turned off, one observes how the gas rises up to fist-sized bubbles quickly without loosening. The exhaust gas from tank B is colored by the penetrating chlorine gas.

Example 2

In turn, the reaction cycle is as shown in Figure 1, but the mixing unit R is now a static mixer. These are four elements of the type marketed by Gebrüder Sulzer AG., Winterthur, Switzerland under the trade name "SMV 8". The total length of the mixing section is 20 cm, the diameter is 5 cm, the ratio of length to diameter is thus 4: 1.

432 kg of tallow fatty acid methyl ester / TME) of 2 ° C (JZ = 52) are filled into container B and vice versa with a throughput of 9 m ³ / h pumps. 98 kg / h of chlorine are introduced, the temperature of the liquid phase rising to 58 ° C. After the chlorine content of the product has reached 18 percent by weight, the mixture is cooled to 41 ° C., the UV lamp in reaction zone G is switched on, and 14.2 kg / h Cl ₂ and 12.8 kg / h SO _{2 are} introduced. until the SO ₂ Cl content is 16.2 percent by weight. The chain chlorine content has not changed. There are obtained 652 kg of methyl chlorot tallow sulfochloride.

Under the process conditions, practically no gaseous reactants can be visually determined in the pumped-over liquid phase after passing through the mixing zone R.

Example 3

In the following example, the continuous process control is described with reference to the attached Figure 2.

The addition of chlorine to the olefinic double bonds of the starting material used is carried out in the first reaction loop. The reaction loop consists of the circulation pump P 1, the static mixing section R 1 and the heat exchanger W 1. 5 m ³ / h of liquid phase of 6 ° C. are pumped around it. There are 26o kg / h of tallow fatty acid methyl ester and 36.4 kg / h of chlorine metered in continuously and 296.4 kg / h of methyl chlorate tallow fatty acid are withdrawn, which are fed to the second reaction loop. This is where sulfochlorination and chlorination take place simultaneously. In the 1st stage of the sulfochlorination / chlorination, consisting of the circulation pump P 2, the static mixing section R 2, and the UV lamp G 1, the heat exchanger W 2 and the separator B 1, 9 m ³ / h of liquid phase pumped at 4o ° C. 51.9 kg / h of C1 ₂ and 20.8 kg / h of S0 ₂ are metered in continuously, and 342.4 kg / h of methyl chlorofatty acid sulfate chloride are drawn off in the direction of the third loop. At the same time, 26.7 kg / h of HCI gas leave the separator B 1. In the second stage of the sulfochlorination / chlorination, a rotor-stator machine (R 3) is installed as the mixing element. 15 m ³ / h liquid phase of 4o ^o C are pumped over and 46.8 kg / h C1 ₂ and 18.2 kg S0 ₂ / h metered in continuously. 24.1 kg / h of HCl gas are separated off in separator B ₂ . There are 383.3 kg / h of chlorotallow fatty acid methyl ester sulfochloride with 16.7 percent by weight of chain chlorine and 15.8 percent by weight of SO ₂ Cl.

Claims (9)

1. Process for the chlorination and sulfochlorination of fat raw materials which are liquid under the reaction conditions, in particular fatty acids and / or their esters, by reaction with chlorine and SO ₂ , in which the liquid feed is circulated through a reaction zone in which it is added to the Circuit fed chlorine and S0 _{2 is brought} to implementation, characterized in that the chlorine and S0 _{2 are} fed in cocurrent with the liquid material and together with this are passed through an intensive mixer during or before entering the reaction zone, the amount of the fed Chlors and S0 ₂ is dimensioned so that the reaction mixture passes through the reaction zone as a practically homogeneous liquid phase. 2. The method according to claim 1, characterized in that one works with an olefinically unsaturated starting material _ and preferably works in several stages such that chlorine is initially attached to the double bonds and then sulfochlorinated, if desired in one of the sulfochlorination preceding or subsequent reaction stage or during the sulfochlorination the chain chlorine content of the feed is increased by substitution reaction. 3. A process according to claims 1 and 2, characterized in _that esters of fatty acids of chain length C ₈ - C ₂₄ subjects with mono- and / or polyhydric alcohols, the process being preferred esters of fatty acids or fatty acid mixtures of natural origin are used. 4. Process according to claims 1 to 3, characterized in that one works in the absence of viscosity-reducing diluents. 5. The method according to claims 1 to 4, characterized in that the intensive mixing of gas and liquid phase by known in the liquid circuit inserted static and / or moving mixing elements, preferably working with static mixing elements that intersect Guide elements in the area of the mixing zone trigger a highly turbulent zigzag flow of the gas-liquid mixture. 6. The method according to claims 1 to 5, characterized in that with flow rates of the liquid phase in the static mixing zone - based on the empty tube - of o, 1 to 5 m / sec., In particular in the range of o, 25 to 2.5 m / sec. the ratio of length to diameter of the mixing section is preferably in the range from 2: 1 to 20: 1. 7. The method according to claims 1 to 6, characterized in that the ratio of the amount of gas supplied to the circulating amount of liquid for both gaseous reactants in the range of o, o5 to 5oo kg of gas / looo kg of liquid, in particular in the range of o, 1 to loo kg Gas /: looo kg liquid lies. 8. The method according to claims 1 to 7, characterized in that in the stage of sulfochlorination with a C1 ₂ / S0 ₂ mixture in a molar ratio of approximately 1: 1. 9. The method according to claims 1 to 8, characterized in that the chlorine addition to the olefinic double bonds at temperatures of 5o to 7o ° C and the sulfochlorination at temperatures of 3o to 5o ° C.

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